Christman, Luther P., author
Westview Press, 1981
Buku Teks
Redstone, Louis G., author
McGraw-Hill, 1978
Buku Teks
Wolper, Lawrence F., author
Jones and Bartlett, 2011
Buku Teks
Cox, Anthony, author
Butterworth, 1981
Buku Teks
Berg, Marc
Routledge, 2004
Buku Teks